arch/x86/kernel/module_64.c

   1 /*  Kernel module help for x86-64
   2     Copyright (C) 2001 Rusty Russell.
   3     Copyright (C) 2002,2003 Andi Kleen, SuSE Labs.
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program; if not, write to the Free Software
  17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 */
  19 #include <linux/moduleloader.h>
  20 #include <linux/elf.h>
  21 #include <linux/vmalloc.h>
  22 #include <linux/fs.h>
  23 #include <linux/string.h>
  24 #include <linux/kernel.h>
  25 #include <linux/mm.h>
  26 #include <linux/slab.h>
  27 #include <linux/bug.h>
  28
  29 #include <asm/system.h>
  30 #include <asm/page.h>
  31 #include <asm/pgtable.h>
  32
  33 #define DEBUGP(fmt...)
  34
  35 #ifndef CONFIG_UML
  36 void module_free(struct module *mod, void *module_region)
  37 {
  38         vfree(module_region);
  39         /* FIXME: If module_region == mod->init_region, trim exception
  40            table entries. */
  41 }
  42
  43 void *module_alloc(unsigned long size)
  44 {
  45         struct vm_struct *area;
  46
  47         if (!size)
  48                 return NULL;
  49         size = PAGE_ALIGN(size);
  50         if (size > MODULES_LEN)
  51                 return NULL;
  52
  53         area = __get_vm_area(size, VM_ALLOC, MODULES_VADDR, MODULES_END);
  54         if (!area)
  55                 return NULL;
  56
  57         return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL_EXEC);
  58 }
  59 #endif
  60
  61 /* We don't need anything special. */
  62 int module_frob_arch_sections(Elf_Ehdr *hdr,
  63                               Elf_Shdr *sechdrs,
  64                               char *secstrings,
  65                               struct module *mod)
  66 {
  67         return 0;
  68 }
  69
  70 int apply_relocate_add(Elf64_Shdr *sechdrs,
  71                    const char *strtab,
  72                    unsigned int symindex,
  73                    unsigned int relsec,
  74                    struct module *me)
  75 {
  76         unsigned int i;
  77         Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
  78         Elf64_Sym *sym;
  79         void *loc;
  80         u64 val;
  81
  82         DEBUGP("Applying relocate section %u to %u\n", relsec,
  83                sechdrs[relsec].sh_info);
  84         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
  85                 /* This is where to make the change */
  86                 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
  87                         + rel[i].r_offset;
  88
  89                 /* This is the symbol it is referring to.  Note that all
  90                    undefined symbols have been resolved.  */
  91                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
  92                         + ELF64_R_SYM(rel[i].r_info);
  93
  94                 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
  95                        (int)ELF64_R_TYPE(rel[i].r_info),
  96                        sym->st_value, rel[i].r_addend, (u64)loc);
  97
  98                 val = sym->st_value + rel[i].r_addend;
  99
 100                 switch (ELF64_R_TYPE(rel[i].r_info)) {
 101                 case R_X86_64_NONE:
 102                         break;
 103                 case R_X86_64_64:
 104                         *(u64 *)loc = val;
 105                         break;
 106                 case R_X86_64_32:
 107                         *(u32 *)loc = val;
 108                         if (val != *(u32 *)loc)
 109                                 goto overflow;
 110                         break;
 111                 case R_X86_64_32S:
 112                         *(s32 *)loc = val;
 113                         if ((s64)val != *(s32 *)loc)
 114                                 goto overflow;
 115                         break;
 116                 case R_X86_64_PC32:
 117                         val -= (u64)loc;
 118                         *(u32 *)loc = val;
 119 #if 0
 120                         if ((s64)val != *(s32 *)loc)
 121                                 goto overflow;
 122 #endif
 123                         break;
 124                 default:
 125                         printk(KERN_ERR "module %s: Unknown rela relocation: %Lu\n",
 126                                me->name, ELF64_R_TYPE(rel[i].r_info));
 127                         return -ENOEXEC;
 128                 }
 129         }
 130         return 0;
 131
 132 overflow:
 133         printk(KERN_ERR "overflow in relocation type %d val %Lx\n",
 134                (int)ELF64_R_TYPE(rel[i].r_info), val);
 135         printk(KERN_ERR "`%s' likely not compiled with -mcmodel=kernel\n",
 136                me->name);
 137         return -ENOEXEC;
 138 }
 139
 140 int apply_relocate(Elf_Shdr *sechdrs,
 141                    const char *strtab,
 142                    unsigned int symindex,
 143                    unsigned int relsec,
 144                    struct module *me)
 145 {
 146         printk("non add relocation not supported\n");
 147         return -ENOSYS;
 148 }
 149
 150 int module_finalize(const Elf_Ehdr *hdr,
 151                     const Elf_Shdr *sechdrs,
 152                     struct module *me)
 153 {
 154         const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
 155                 *para = NULL;
 156         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 157
 158         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 159                 if (!strcmp(".text", secstrings + s->sh_name))
 160                         text = s;
 161                 if (!strcmp(".altinstructions", secstrings + s->sh_name))
 162                         alt = s;
 163                 if (!strcmp(".smp_locks", secstrings + s->sh_name))
 164                         locks= s;
 165                 if (!strcmp(".parainstructions", secstrings + s->sh_name))
 166                         para = s;
 167         }
 168
 169         if (alt) {
 170                 /* patch .altinstructions */
 171                 void *aseg = (void *)alt->sh_addr;
 172                 apply_alternatives(aseg, aseg + alt->sh_size);
 173         }
 174         if (locks && text) {
 175                 void *lseg = (void *)locks->sh_addr;
 176                 void *tseg = (void *)text->sh_addr;
 177                 alternatives_smp_module_add(me, me->name,
 178                                             lseg, lseg + locks->sh_size,
 179                                             tseg, tseg + text->sh_size);
 180         }
 181
 182         if (para) {
 183                 void *pseg = (void *)para->sh_addr;
 184                 apply_paravirt(pseg, pseg + para->sh_size);
 185         }
 186
 187         return module_bug_finalize(hdr, sechdrs, me);
 188 }
 189
 190 void module_arch_cleanup(struct module *mod)
 191 {
 192         alternatives_smp_module_del(mod);
 193         module_bug_cleanup(mod);
 194 }